The story of coffee and tea

Tea comes from the leaves of Camellia sinensis, a plant native to the region spanning southwest China and neighbouring areas. Chinese legend credits the emperor Shennong with discovering tea when leaves blew into his boiling water, but the earliest firm evidence of tea drinking comes from China around the second century BCE.

During the Tang dynasty, tea became part of everyday life, and in the eighth century Lu Yu wrote The Classic of Tea, describing its cultivation and preparation. Buddhist monks brought tea to Japan, where it developed into the tea ceremony, a ritual of hospitality and mindfulness.

Coffee plants are native to Ethiopia. A popular legend tells of a goat herder named Kaldi who noticed his goats became energetic after eating coffee cherries, but the story was first recorded centuries later and is probably not historical.

Reliable evidence shows coffee being brewed in Sufi monasteries in Yemen by the fifteenth century, where it helped worshippers stay awake for night prayers. From Yemen, coffee spread across the Islamic world, and coffeehouses became popular meeting places in cities such as Mecca, Cairo and Istanbul.

• The first coffeehouse in England opened in Oxford in 1650, and London soon had hundreds.
• London coffeehouses were called penny universities, since for the price of a coffee anyone could join discussions.
• Lloyd's of London began in Edward Lloyd's coffeehouse, where merchants and ship owners met to arrange insurance.
• Authorities in several countries tried to ban coffeehouses, fearing political gossip and sedition.
• Teahouses played similar social roles in China, Japan, Russia and elsewhere.

Tea arrived in Europe in the early seventeenth century through Dutch traders and became hugely popular in Britain. To pay for Chinese tea, the British East India Company sold opium grown in India to China, despite Chinese bans. Conflicts over this trade led to the Opium Wars of 1839 to 1842 and 1856 to 1860, which forced China to open its ports and cede Hong Kong.

Britain also sought to grow tea itself. In the 1840s the botanist Robert Fortune smuggled tea plants and knowledge out of China, and British planters established vast tea estates in India, especially in Assam and Darjeeling, and later in Ceylon, now Sri Lanka, often under harsh conditions for workers.

Europeans established coffee plantations in their tropical colonies. The Dutch grew coffee in Java, the French in Saint-Domingue, now Haiti, and later Brazil became the world's largest producer. Much of this production depended on enslaved labour; Brazil did not abolish slavery until 1888.

In the American colonies, tea was taxed by Britain, and the Boston Tea Party of 1773, when colonists dumped tea into Boston Harbor, became a symbol of resistance on the road to the American Revolution.

Tea is the most widely consumed drink in the world after water, and coffee is one of the most traded agricultural commodities. Both contain caffeine, a stimulant that blocks adenosine, a chemical in the brain that promotes sleepiness.

Most of the world's coffee is grown by millions of smallholder farmers in countries such as Brazil, Vietnam, Colombia and Ethiopia, many of whom earn very little from the final retail price. Fair trade certification and direct trade schemes try to improve farmers' incomes, while climate change threatens coffee-growing regions that depend on specific temperatures and rainfall.